New methods for rapid remineralization of teeth and desensitization of dentin will be developed using carbonate, temperature and 2-step application to control the deposition. Three kinds of solutions with different concentrations and application methods will be used: (1) stable cold solutions containing maximum concentrations of calcium and phosphate under pressurized CO2 atmosphere. Due to the carbonic acid and lower pH under pressurized CO2 atmosphere, these carbonated solutions are stable and will precipitate when applied under oral conditions, due to the increase of the pH (a consequence of the escape of CO2) and temperature in solutions: 2) highly supersaturated cold solutions under CO2 atmosphere prepared just before application by mixing two carbonated cold solutions one containing calcium and the other containing phosphate and fluoride: and (3) tow-step solutions with an application of a solution containing high concentrations of phosphate and fluoride, followed by a solution containing a high concentration of calcium. All three solutions when applied, will rapidly precipitate apatite precursors in needed sites which then convert to apatite in situ. The specific aims are to: (1) study the effects of CO2 pressure on the ph. composition and stability of calcium phosphate solution; (2) determine factors affecting the precipitation and maturation of calcium phosphates in the above three kind of solutions: (3) formulate solutions based on the above findings; and (4) test in vitro the efficacy of the formulated solutions in remineralizing artificial caries, in resisting acid challenge, and in decreasing the fluid flow rates through dentin. The methods include pH and turbidity measurements, titration in a pH stat, X-ray diffraction. Raman microprobe and chemical analysis, The degree of remineralization and resistance to acid challenge will be measured by means of polarized light microscopy and qunatitative image analysis of microradiographs. Rapid remineralization may prevent, arrest or reverse the progress of caries and sensitivity and reduce the need for restorative procedures.